Overview

The humanoid Cylons have become the quintessential Cylon form - the modern Centurions are not fully sentient like their predecessors and answer to the humanoids. These Cylons biologically mimic human form so completely that they are nearly undetectable to current Colonial technologies. Humanoid Cylons have the capacity to emulate many human physical acts, including sex. Their "programming" is such that they genuinely possess human personality traits (affection, love, sex drive, jealousy, sadness, anger, hatred, sense of humor, fear, happiness, religious faith, etc.).

The original purpose of the humanoid Cylons was to simply serve as the next step in Cylon evolution (TRS: "No Exit"). However, the fact that they are designed to be as human-like as possible in appearance, internal anatomy and behavior makes them perfect spies. The humanoid Cylons are responsible for masterminding the complete destruction of the Twelve Colonies through their use of sabotage and infiltration.

Origins

Although at least one human-shaped robot existed in the Twelve Colonies of Kobol prior to the First Cylon War (housing a copy of the consciousness of Zoe Graystone), this was not a truly biological android and her connection to the later humanoid Cylons is unclear. All that is known about Graystone's android body is that the bath from which she emerged resembled a resurrection tank, her mother the plastic surgeon Amanda Graystone gave her skin, and she may have been in contact with the five survivors of the Thirteenth Tribe (CAP: "Apotheosis", DVD commentary for "Apotheosis").

During their forty years of isolation, the Cylons developed humanoid models [2]. The first step in their evolution from pure machines to organic beings was known as the "First Hybrid." Other Hybrids were later created to control baseships (TRS: "Razor"). Hybrid models are not fully humanoid and cannot live on their own, thus are considered an evolutionary dead end.

The new humanoid Cylons were created by the five survivors of an earlier generation of humanoid Cylons from Earth in exchange for the Centurions ending the Cylon War. These five early generation Cylons (now known as the "Final Five") are the descendants of Cylons created by humans on Kobol thousands of years ago. These humanoid Cylons were the Thirteenth Tribe that left Kobol and settled Earth.

The Five created the Number One model first and named them John. They initially developed eight humanoid models and copied each of them many times over. However, the seventh model, Daniel, was destroyed by Number One out of jealousy. Number One (also known as "Cavil") contaminated the amniotic fluid in which the Number Seven copies were maturing and then corrupted the genetic formula.

Physiology and Psychology

Humanoid Cylons are not merely robots with a human appearance, they possess actual flesh and blood. They are visually indistinguishable from humans down to the cellular level, but not completely at a molecular level. Dr. Gaius Baltar is able to create a detector that can distinguish Cylon from human, but rarely uses the device to a positive end (TRS: "Litmus"; "Tigh Me Up, Tigh Me Down"). Deceptions on the part of Dr. Baltar in regards to the true nature of sleeper agent Sharon Valerii lead to the detector being inaccurately labelled useless and abandoned (TRS: "Resistance"; "He That Believeth In Me"). The Cylons themselves have accurate methods for testing biological samples and determining whether they are human or Cylon (TRS: "Sometimes a Great Notion").

Each humanoid Cylon has the same face, stature, hair, eye and skin color, sex, apparent age, and other biometrics as all the others of his or her model. Some copies choose to make cosmetic differences. Examples include D'Anna Biers, Gina Inviere, and a Number Six copy with black hair (TRS: "Torn"). In addition, each copy appears to start with the same basic personality, but each personality grows more distinct due to their individual experiences. For example, any two random Eights are more or less interchangeable, but Sharon Valerii and Sharon Agathon have become highly individuated.

Humanoid Cylons' memories and programming can be tampered with. The Number Ones altered the memories of the Number Twos, Number Threes, Number Fours, Number Fives, Number Sixes and Number Eights to remove knowledge of the Final Five from them and programmed them not to think or talk about the Five. The Ones also blocked the real memories of the Final Five and imprinted them with fake memories so that they believed they were human. The same was done to Sharon Valerii, but in her case her original memories could be awakened with a trigger so that she would commit acts of sabotage against the human fleet.

Valerii is the only such sleeper agent known. Other Cylon infiltrators are fully aware of their true nature. The Final Five were never infiltrators as such, rather the Ones made them live through the Cylon Attack as "humans" in order to teach them a lesson.

The emotionally scarred Number Six copy known as "Gina Inviere".

Humanoid Cylons are susceptible to the same emotional traumas and joys that humans are, as they cannot "turn off" their ability to feel pain or other emotions (TRS: "Escape Velocity"), further proving that personalities are a real part of their psyche. A case in point is a copy of Number Six, known as Gina Inviere, who is physically and sexually assaulted repeatedly by the crew of Pegasus. These repeated assaults lead to Inviere's near-catatonic state and suicidal desires at the time Pegasus discovers the Fleet (TRS: "Pegasus").

Humanoid Cylons can sleep and dream[3], however they can live without doing so, and the Ones have reprogrammed themselves to prevent sleep, wishing to avoid nightmares.

Reproduction is important to the Cylons, because one of their God's commandments is to "be fruitful". Both male and female Cylon models possess reproductive systems which should be fully functional, but have a flaw that is not properly understood. The Ones, Twos, Fours, and Fives have tried to impregnate the Threes, Sixes, and Eights many times, but all these attempts at sexual reproduction have failed[4]. The Cylons try to interbreed with humans to subvert this deficiency, creating hybrid offspring. "Farms" were set up across all the occupied Colonies where survivors, including young fertile women of child-bearing age, were rounded up, placed under heavy sedation and turned into "baby machines" through artificial insemination. There also farms for male humans, plus in vitro experiment labs, etc (TRS: "The Farm" podcast). If a captured human agrees to cooperate, he or she is instead set up with a Cylon sexual partner on a voluntary basis. However, these methods have all been unsuccessful thus far.

Another drastically different approach is taken by attempting to conceive a child through a bond of love, because of the Cylon belief that "God is Love". Helo and Athena's love-child, Hera is the lone success story of the relatively short history of Cylon sexual reproduction (TRS: "The Farm"). More recent conceptions of human-Cylon hybrids or pure Cylon offspring have either been proven untrue (in the case of Galen Tyrol's child Nicholas Tyrol) or miscarried during pregnancy (Saul Tigh and Caprica-Six's unborn child Liam Tigh).

The bodies of humanoid Cylons have stamina and strength above human average, and are designed to destroy or resist commonly dangerous human diseases[5], although they are not immune from all contagions[6]. In keeping with their desire to be a better human, however, the Cylons did not or could not further improve on other characteristic design flaws of the human body.[7] Humanoid Cylons are heavily fortified to resist damage from intense radiation fields that would kill a human after short exposure (TRS: "The Passage"), but they are still susceptible to damage from certain types of radiation or trauma (TRS: "Miniseries, Night 2"). Despite their resistance to certain forms of energy, humanoid Cylons, unlike the Cylon Centurion, cannot be made "bulletproof" and are as susceptible as humans to piercing or blunt force weapons (TRS: "The Farm"; "Precipice"; "Hero"). They require oxygen to live, and thus can be killed by suffocation (TRS: "Torn"; "The Face of the Enemy"; "No Exit").

Some Cylons, like some humans, are spiritually sensitive and have been known to receive visions. For example, D'Anna Biers, Caprica-Six, and Sharon Agathon (TRS: "Hero"; "Crossroads, Part I"). The Number Two model regularly claims to see patterns and have insight into future events (TRS: "Flesh and Bone"; "Occupation").

Cylon Religion

The Cylons follow a monotheistic religion to varying extents. Fanatical devotion to God is the central part of Number Two's character, whilst the Sixes, Threes, and to a lesser extent the Eights also have strong faith. The Number Ones are atheistic. Fours' and Fives' views are not so well known, but they too take the "non-religious side" in the Cylon Civil War. The Cylon belief system is handed down from the original Centurions and the Final Five.

As a humanoid Cylon downloads after being killed, it is apparent that the Cylon's memories are automatically stored for future use. This means that, in addition to the transmission of the memories to the slain Cylon's own resurrected self, another copy of that specific model can access these memories if they so choose. Once these memories are implanted they become as real to the receiving Cylon as their own original memories. This uploading of memories seems to be involuntary, as Sharon Agathon had no reason to do such a thing when she died, but another Cylon must choose to access them (TRS: "Rapture"; "The Hub").

The humanoid Cylons' psychology is based on what they simply refer to as "projection". Essentially an enhanced form of a self-induced and controlled hallucination, projection is how they choose to see the world around them, in any form they wish, whenever they wish. For example, if a Cylon were standing in a hallway, they could choose to see it as a forest filled with birds, trees, and sunlight. This mode of visualization is pleasing to humanoid Cylons (TRS: "Torn")[8]. Cylons can share these virtual worlds with each other (TRS: "Someone to Watch Over Me").

Although they cannot do so remotely or wirelessly, humanoid Cylons can interface with a computer system or computer network by photo-electrical means. To interface directly with a Colonial ship's system the Cylon must insert a cable into his or her own arm, which is painful (TRS: "Flight of the Phoenix"). The process is preferably carried out by touching a data-font of the Cylon datastream[9]. This might be possible through the use of bio-luminescent and photosensitive cells in their hands. Once interfaced, they can rewrite code to purge or create a computer virus, send transmissions to other computer systems, or calculate FTL jump coordinates (TRS: "Lay Down Your Burdens, Part I").

Anders's "red eye" moment.

The presence of a water-like fluid as an integral part of the basestar, the ability to interface photo-electronically through subdermal and dermal contact, and the fact that humanoid Cylon are anatomically indistinguishable from human beings, implies that the techniques used in their creation are advanced enough to incorporate cybernetic functions into their design without the use of specific internal structures other than human-like organs.

A humanoid Cylon, or at least one with the strange brainwaves exhibited by Anders after being shot in the head, can be wired into a ship like a Hybrid by means of the datastream and a tank similar to a Hybrid's own (TRS: "Islanded in a Stream of Stars"). The datastream in this tank was used by the Final Five to access and combine their own memories of Resurrection technology (buried memories in the case of Saul Tigh, Galen Tyrol, and Tory Foster), then send it to the Colony's Hybrids. This process was unspecific, however, and gave them full access to each other's recollections for a moment (TRS: "Daybreak, Part II").

The Thirteen Cylon Models

By the time of the Cylon attack on the colonies, there are twelve models of humanoid Cylons (Miniseries). These can be divided into two separate groups, the "Significant Seven"[10] and the "Final Five". The Significant Seven were once eight in number, but Number Seven is no longer extant (TRS: "No Exit"). Only six models survive to settle on the new Earth, namely Saul Tigh, Ellen Tigh, Galen Tyrol, Number Two, Number Six, and Number Eight (TRS: "Daybreak, Part II").

The Significant Eight have numerical designations and were designed based on personality archetypes the Cylons had witnessed in humanity, however this is not true of the Final Five. All the Significant Eight models except the Sixes have come to be associated with a particular "human name", and even other Cylons will refer to "Leobens", "Sharons", "Daniels", "D'Annas" and so on.

Significant Eight

The seven surviving models of the Significant Eight were the first seven Cylons to be revealed to the Colonials. With the exception of Number Seven, whose entire line was sabotaged (TRS: "No Exit"), there are many copies of each model, all totaling in the millions according to Number One and Ellen Tigh. The identities of these mechanized copies are determined by their model and each model is unique (TRS: "Six of One"). These models were designed by the Final Five (TRS: "No Exit").

One of the Number One models poses as a Colonial brother named Cavil, a lay clergyman in the Fleet. This Cavil is later revealed to be the one responsible for the destruction of the Twelve Colonies and is indicated to be the same copy as the one that led the Cylon Civil War.

Ones do not appear to subscribe to overall theology of the Cylons, but adhere to group consensus, and often are persuasive leaders. Ones have displayed a condescending attitude toward the beliefs of the other six known Cylons at times.

In several instances, the Ones advocate dark, draconian solutions to the insurgency on New Caprica that reveal a militant zeal equaling that of Numbers Three and Five.

This Number One model in particular seems to be in something approaching a leadership role on one of the basestars (TRS: "Six of One"). This model assumes some authority and wields influence over the others, yet decisions are still reached through majority vote. However, this is soon overturned by the rebellion of the Cylons led by Natalie, a Number Six, and the body of this One is killed by Centurions. The resurrected Cavil assumes leadership of one faction in the Cylon Civil War.

The Number One model was the first model created by the Final Five, and assisted them in creating the other models of the Significant Eight. Unfortunately, the Number Ones eventually rebelled against the Five and exiled them to the Twelve Colonies with their memories erased. Prior to this, they eradicated the entire Number Seven model line out of jealousy, and secretly programmed their brothers and sisters of the other six models to lose all knowledge of their makers. The Number One model was given the name John by the Final Five, but does not like this appellation.

Number Two, better known as Leoben Conoy, has shown to be mystically oriented--making references to the oneness of the universe, the illusion of time, etc.--and claims to be prescient on some level, albeit with a known propensity for intermixing truth with falsehoods. He is first discovered on Ragnar Station shortly after the Holocaust on the Twelve Colonies, claiming to be a scavenger and arms dealer (TRS: "Miniseries, Night 2").

Two can be likened to the serpent of the Genesis tale in the Earth Christian Bible, taunting people with knowledge, then watching as the negative consequences come into devastating fruition. Copies have likely been encountered by the Caprica Resistance, as Samuel Anders recites in jest some the "swimming in the stream" comment made by another Number Two copy captured in the Fleet (TRS: "Flesh and Bone",; "The Farm").

First seen posing as a reporter from the Fleet News Service, this model created a documentary about the crew of Galactica - which was later shown on Cylon-occupied Caprica to a theatre full of Cylons, including a second copy of Number Three (TRS: "Final Cut"). Threes are among the most calculating and duplicitous models shown to-date, even manipulating and deceiving other models if they feel warranted, though they've got nothing on the duplicity and manipulations of the Number Ones. The copy that tried to box Sharon Valerii exhibited these characteristics strongly (TRS: "Downloaded").

After the Threes defy other Cylon models in their attempt to discern the identity of the five missing Cylon humanoids, the other Cylons conclude that the Three model has an inherent flaw that threatens their overall reliability. After the failure on the algae planet to gather information on the path to Earth, the Cylons have all Number Three models boxed indefinitely.

One of the goals of the rebel faction in the Cylon Civil War is to unbox D'Anna and learn what she knows. She is actually unboxed by Cavil and Boomer, who want to her to speak to the rebels and get them to stop fighting, but this discussion is interrupted by a joint Colonial and rebel Cylon attack on the Resurrection Hub (TRS: "Rapture"). With the Resurrection Hub destroyed in the battle, D'Anna is the only Number Three copy in existence. She is retrieved and assumes leadership of the rebels to make contact with the Final Five, eventually reaching Earth with the Colonial fleet, but decides to stay behind there and die, following the revelation that Earth is a barren nuclear wasteland (TRS: "The Hub"; "Revelations"; "Sometimes a Great Notion").

The first encountered copy of this model appeared under the alias "D'Anna Biers", and the D'Anna name is used to describe the model as a whole.

The Number Four model is first encountered by Kara Thrace on Cylon-occupied Caprica. Posing as a doctor under the name Simon, this Number Four is actually involved with the Cylon hybridization program. Simon resembles a tall, somewhat thin middle-aged black man who speaks in a comforting strong voice (TRS: "The Farm"). Simon is a model based primarily on human intellectualism and logic[11]. A Four model also infiltrated the Fleet prior to the occupation of New Caprica. Posing as a doctor enlisted in the Colonial Fleet under the name of Simon O'Neill, he escapes the destruction of the colonies aboard the Cybele with his adopted daughter and is later reunited with his wife Giana who he truly loved. He killed himself beyond resurrection range ultimately to prevent himself betraying the Fleet. Another Four served as the team doctor for the Caprica Buccaneers at the time of the attack and fought as a part of Anders' resistance. He was found out when the Resistance rescued Starbuck from another copy and was presumably killed for being a Cylon. In any case, the model is now known to the general populace, many humans likely saw a Number Four model during the occupation and Starbuck revealed his existence upon her return to the Fleet.

The Number Fours are part of Cavil's faction in the Cylon Civil War, and fill a crucial medical role in his schemes, being recruited to transfer vital information on resurrection technology from Ellen Tigh's brain, and after the kidnapping of Hera, to examine and eventually dissect the hybrid child. To the end, the Number Fours trust in cold logic and mathematics when considering the chances of Galactica emerging victorious in the Battle of the Colony.

This model attempts to sow the seeds of discontent or confusion, particularly during crucial life-threatening situations, and endeavors to undermine authority that threatens his objectives (TRS: "Miniseries"). Number Five models are more covert than others, assuming an ordinary "everyman" appearance that's blended in what may seem to be insignificant behind-the-scenes issues (such as converting Galactica into a museum). Of all the models thus far, the Number Five models are among the most militant, fanatic, and consistent in message and objectives to the Cylon objectives, whether he is dispassionately discussing the fate of humanity with his comrades or attempting to kill or maim Colonials in a suicide bomb attack (TRS: "Litmus").

Viewers first meet a Number Five during a tour of Galactica with other Colonial citizens (possibly the press) at the start of the Miniseries, but are not sure of the Cylon's true identity until the Miniseries' conclusion.

This is the first humanoid Cylon model shown to viewers at the start of the Miniseries.

Stunningly beautiful, promiscuous and sensual, this model utilizes the human need and desire for sexual relations to her advantage. She tends to be very religious and monotheistic. Number Six desires to know what it is to be alive. Sixes have been described as "usually so hardcore", referring to their tendencies towards violence.

Sixes are the only model who appear not to have one particular "human name"; copies have appeared under the aliases "Shelly Godfrey", "Gina Inviere", "Natalie Faust", "Lida", "Sonja", and "Caprica" (in honor of her work on Caprica towards the destruction of the Colonies). She seems not to have been known by any name by Gaius Baltar, even as the two formed a love to last eternity before the fall on Caprica.

Six is also the only model known to exhibit significant variations in appearance -- several different hairstyles and hair colors have been noted -- as well as noticable differences in personality, ranging from idealistic (Caprica) to assertive and take-charge (Natalie) to wide-eyed and innocent (Lida).

Shortly after the attacks, Baltar began experiencing interactions from an entity (informally dubbed Messenger Six) that resembles the version of Caprica-Six that seduced him prior to the attacks. It is unclear what relation if any that Messengerl Six -- that only Gaius Baltar can see and hear -- has to the physical Sixes. Caprica-Six, meanwhile also began to experience interactions with a Virtual Baltar after the attacks.

The Number Sixes are part of the rebel faction, of which Natalie Faust was originally the leader, in the Cylon Civil War.

Number Seven, also known as "Daniel", is a previously-undisclosed model whose existence is revealed by Number One and members of the Final Five who have recovered their memories (TRS: "No Exit"). This model is believed to be defunct due to a sabotage by Number One prior to the Second Cylon War. The Daniel model was artistic and sensitive, and had a close relationship with Ellen Tigh, which led to murderous fraternal jealousy on the part of the Cavil model. Nothing is known about this model's appearance.

It is possible that Number Seven was named after Daniel Graystone, the inventor of the Twelve Colonies' Centurions.[12]

Number Eight is generally a saboteur assigned to infiltrate Colonial military units and is likely programmed to use any Colonial munitions to cause havoc (TRS: "Water"). The Number Eight model is the closest witnessed humanoid Cylon model to show its abilities as a soldier. This model has shown naiveté in many matters. She is religious like most other Cylon models, has demonstrated that she can love, and is capable of being impregnated by a human (TRS: "Six Degrees of Separation"; "Kobol's Last Gleaming, Part II").

The original sleeper agent copy of this model appeared under the name "Sharon "Boomer" Valerii." Her copy on Caprica used the same identity before marrying Helo and joining the Colonial fleet.

The Number Eights are part of the rebel faction in the Cylon Civil War, with the exception of Boomer (who is Cavil's consort) and Athena (who is part of the human fleet, and thus merely allied with the rebels).

Final Five

The identities of the missing five Cylon models remain a mystery long after the revelation of the identities of the "Significant Seven".

Gaius Baltar, who knows there are twelve extant Cylon models yet has only observed seven aboard the Cylon baseship, coins the term "Final Five" for the five that are missing. Caprica-Six informs him that the seven do not discuss or know the identities of the five (TRS: "Torn"). After entering the Ionian Nebula, four major players in the human fleet become awake to the fact that they are Cylons: Galen Tyrol, Saul Tigh, Samuel Anders and Tory Foster. They were previously unaware of their nature, because they were boxed by the Number One model and introduced to the Twelve Colonies one at a time with fabricated memories and histories (TRS: "No Exit"). They keep the knowledge that they are Cylons to themselves until a standoff between Galactica and the rebel baseship forces them into the open. The identity of the final Cylon remains a mystery until Saul Tigh recovers fragments of blocked memory in the ruins of Earth and realizes that it was his wife, Ellen (TRS: "Sometimes a Great Notion").

Although the Final Five are genetically of the same race as their creations, and their own earliest ancestors were constructed, their nature differs from that of the Signficant Seven in that each of them was originally born to Cylon parents on Earth. Thus, they only ever had names, not numbers. Unlike the many copies of the Significant Seven, there is only one active version of each of the Five at a time. However, like the Significant Seven, they are capable of downloading into identical duplicates if killed, as long as the Resurrection Hub exists; indeed, they are the inventors of the resurrection system used by all humanoid Cylons and organic Raiders. Their bodies at the time of the First Cylon War and the Fall of the Twelve Colonies are not their original bodies, which were destroyed by the nuclear warfare on Earth.

Prior to the Cylon assault on the Colonies he was a Pyramid player for the Caprica Buccaneers and was leading his team in high-altitude training in the mountains outside of Delphi when Caprica was attacked. Anders and the resistance movement conduct acts of terrorism against the Cylons for months with variable success until their eventual rescue by Kara Thrace.

After becoming aware of his Cylon nature Anders joins the Demetrius's crew on its mission to find Earth, an action which eventually leads to an unintended conflict with Felix Gaeta. The events on board Demetrius lead to the unboxing of D'Anna, who is aware of his nature as a member of the "Final Five".

When President Roslin makes the decision to keep the new-born Cylon/human baby as far away from Sharon Agathon and the Cylons as possible, it is Tory who chooses Maya ro raise the child. During the occupation of New Caprica Tory is responsible for ensuring the safe transport of Maya and Hera off the planet, but she fails at this task.

Since the events of the Ionian nebula Tory appears to have embraced both being a Cylon and her own version of Baltar's teachings, allowing her to by-pass feelings such as guilt and adopt an almost hedonistic approach to life. She declares herself to be "perfect", something that uneases fellow Cylons Tigh and Tyrol, and is in marked contrast to Tigh's and Caprica Six's guilty consciences (TRS: "Escape Velocity"). She has also displayed a cold-blooded streak, murdering Cally Tyrol when the wife of Galen Tyrol discovers the four's Cylon nature. (TRS: "The Ties That Bind")

Ellen Tigh was the wife of Colonel Saul Tigh and a survivor of the Cylon Holocaust. Ellen claims to have been on Picon at the time of the Cylon attack, on her way back home for a reunion with her husband. When the airport was hit in the attack, she claims an anonymous hero found her unconscious body and got her on to one of the last transports out, where she had been unconscious aboard the Rising Star for some three weeks prior to Adama finding her. It's ultimately revealed that when the attack happened she was in a bar on Picon talking to a mysterious stranger who didn't give her his name. The bar she was in was destroyed by a shockwave from a nuclear blast and she was severely injured, but survived. Cavil kept her alive as he felt she still hadn't learned her lesson and escorted her to the medical transport Rising Star where she spent the three weeks recovering from her severe injuries after the ship lucky enough to make it to Galactica.

Ellen is well known for her sexual promiscuity and her desire for power. After Adama's attempted assassination, she encourages her husband to take extreme measures to assert his authority, sometimes in contrast to the more reasoned approaches he is proposing. Her pressures lead her husband to drink and take unwise steps, including a standoff on the Gideon that leaves four people dead.

One year after New Caprica is colonized, Ellen Tigh settles on the planet. Her husband joins her later, after Admiral Adama's insistence. After the Cylons arrive Ellen begins a relationship with Cavil to protect her husband. When her collaboration is discovered the resistance leaders compel Saul Tigh to execute his wife. Saul carries out the execution by poisoning Ellen's drink prior to the Battle of New Caprica (TRS: "Exodus, Part II").

In a flash of memory on Earth, Saul Tigh realizes that Ellen is the last of the Final Five.

It is later revealed that Ellen did in fact survive her husband killing her: she downloaded into a new body on a Resurrection Ship after which Cavil kept her prisoner and a secret from all of the other Cylons but Boomer. With her resurrection she regained all of her true Cylon memories and had a much different personality then when she was originally on the show. It's revealed that it was in fact a Cavil that put her on that transport. Cavil plans to open her brain for information on resurrection technology but she escapes with the help of Boomer and makes it back to Fleet, where she attempts to assert leadership over her four colleagues. (TRS: "Deadlock")

Tigh has a somewhat dysfunctional marriage with his wife Ellen. Soon after her reunion with Tigh, he returns to drinking and often finds himself acting as an unknowing pawn as his wife plays her political schemes. After the attempted assassination of Adama by Sharon Valerii, Tigh temporarily acts as Commander of the Fleet, a position which almost leads to catastrophe.

During the occupation of New Caprica, Tigh commands the resistance. In the months spent on the planet Tigh suffers many harsh losses, including losing an eye to the Cylons and the death of his wife.

After learning of his Cylon nature Tigh finds himself repeatedly visiting Caprica-Six in the brig in an attempt to understand and come to grips with his unwanted identity, a course of action that is not without consequences.

Galen Tyrol, often referred to as "Chief", is the highest ranking NCO remaining aboard Galactica. Tyrol is demoted for a while until Peter Laird is KIA before being reinstated as Galactica's "Chief" again (No Exit). He is a respected and well liked officer on Galactica, and has great respect for Commander Adama. Tyrol attempts to model his own style of command after Adama, unknowingly modeling even the extremes of his style, such as the reckless actions he sometimes makes in support of his subordinates.

For several months prior to the Cylon attack, and in its aftermath, Tyrol was engaged in an affair with Lieutenant Sharon Valerii, one of Galactica's Raptor pilots, a relationship which was forced to end. Tyrol is part of the team assembled on the ill-fated recon to Kobol on the Raptor 1, which then crashlands near the ruins of the Tomb of Athena.

Tyrol has difficulty coping with the revelation that he is a Cylon, beginning to cut himself. Although trying to act normally, Tyrol's changed behavior eventually has an effect on his marriage. He blames himself for Cally's apparent suicide, but finds himself unable to pull the trigger when he tries to kill himself.

The Thirteenth Tribe

The thirteenth tribe consisted of an earlier generation of humanoid Cylons first created on the planet Kobol. They colonized Earth after the exodus from Kobol, going their separate ways from the twelve human tribes that settled the Twelve Colonies. Because they reproduced sexually, they were a diverse population without a limited number of models. Their remains, when tested using procedures known to the Significant Seven, match as Cylon. The Thirteenth Tribe destroyed itself in a nuclear holocaust (TRS: "Sometimes a Great Notion"). The Thirteenth Tribe originally used resurrection technology to sustain themselves, but this was lost after they began to procreate naturally. The Final Five are the last five survivors of this Cylon civilization, having rediscovered resurrection technology (TRS: "No Exit"). The five were also the only surviving members of the humanoid Cylon race until they created the Significant Eight.

Human/Cylon Hybrids

Gaius Baltar's internal Number Six regularly insists that Hera is actually the child of herself and Baltar, though there is no physical reason yet presented to justify that claim.

For some time Hera was hidden away from both humans and Cylons, and believed to be dead by her parents. President Laura Roslin had the baby hidden with Maya as her adoptive parent. Despite Roslin's attempts to protect the child on New Caprica, Hera is later found by the Cylons (TRS: "Exodus, Part II").

After Hera's mother discovers that her daughter is alive, she uses her ability to download to transport to the Cylon ships, and manages to convince Caprica-Six to return the child to Galactica for medical treatment for a possible intestinal blockage, which the Cylon doctors, lacking pediatric knowledge, were unable to comprehend (TRS: "Rapture").

All humans living on the second Earth 150,000 years after the Colonial holocaust are descendants of Hera, making them all a combination of human and Cylon (TRS: "Daybreak, Part II").

A child, Kacey Brynn, is presented by a Number Two model to Kara Thrace as a hybrid offspring purportedly created with their genetic material in the episode "Precipice". The Cylon's ruse is revealed when Kacey's real mother later claims the child, who is a normal human girl (TRS: "Exodus, Part II").

Liam Tigh

Liam is a fully Cylon child conceived by Saul Tigh and Caprica-Six. His conception comes as a great surprise to the rebel Cylons after so many failed attempts, and leads them to believe that it is possible for them to build a self-reproducing Cylon civilization away from the Colonial fleet, just like the original Thirteenth Tribe. Tory Foster and Galen Tyrol vote in support of this plan. However, the child is miscarried while Caprica-Six is still only four months pregnant, closing the door on the notion of remaking a separatist society of pure Cylons.

Speculated Infiltrators

See the Humanoid Cylon speculation article for analysis on characters and their likelihood of being a humanoid Cylon, based on episode information.

Notes

Ron D. Moore stated in an interview with TheFandom.com, "There is no original human Sharon. The idea is not that there was likely an original human model that they were copied from. The idea was that these models of Cylon were sort of developed out of their own study of us. The Cylons on some level looked at humanity and said 'You know what? There's really only 12 of you.' If these are the 12, and sort of if you look at them they each represent different archetypes of what humanity is." This established as what was thought to be canon that:

There are precisely twelve human Cylon models. The other varieties of Cylon spacecraft or fighters are not factored into this count of 12 models.

None of the humanoid Cylons was ever an actual human.

Although John Cavil was designed to look like Ellen's father John, a humanoid Cylon from Earth.

Though, It is possible that Number Six's appearance was based off the appearance of the 'woman messenger' that appeared to Sam Anders. This would potentially explain the lack of a given personal name for the model.

Kevin Murphy has stated in an interview with The Caprica Times that the production team for the series Caprica discussed the idea that the Sixes and Eights were based on Zoe Graystone and Tamara Adama, respectively, although this was never established onscreen. Even if the Sixes and Eights were inspired by Zoe and Tamara, they are obviously not exact copies.

The twelve models are based on archetypes determined by the Cylons that form what they perceive were the specific kinds of human behavior and/or personality, distilled into twelve varieties.

However, much of it has been disproven or called into question by revelations about the nature of Cylons in season 4 episodes, particularly in "No Exit":

Although the twelve model count is accurate - when Caprica-Six states this, there are indeed only twelve models extant - including the lost Number Seven in the Cylon count raises the total number of models to 13. Including members of the original Thirteenth Tribe who died on Earth raises the number much further than 13.

Cavil was revealed to be based on Ellen's father, a Thirteenth Tribe Cylon, raising the possibility that other models cauld be based on individuals known by the Final Five in their original lives.

Unlike the eight numbered Cylon models, the Final Five are the product of natural reproduction by members of the Thirteenth Tribe, so they could not have been designed around specific personality archetypes, although this possibility is still open for the numbered Cylons.

According to Cavil in "Exodus, Part I", the pain associated with each successive download is worse than the one before. The first download feels like little more than a headache, but the third feels like someone has rushed a white hot poker through the head. However, this might be a subjective feeling that varies with model and circumstances. Sharon Agathon's report in "Scar" supports Cavil, but a Number Three considers her last download to be rejuvenating (Downloaded).

Some characters refer to humanoid Cylons as "skinjobs". This is a reference to the film Blade Runner in which Edward James Olmos has a supporting role. In the movie "skinjob" is used as an insult to replicants, which are bio-mechanical robots made to look human.

According to Ron Moore, the Final Five Cylons, unlike the Significant Seven, "do not" have model numbers [14].

References

↑ Viewers initially lacked an authentic term to call the humanoid Cylons by during Season 1. Here on the Battlestar Wiki, the descriptive term "Humano-Cylon" was used for a time. Dialogue in several episodes throughout Season 2 has canonically established "Cylon agent" to refer specifically to Cylon infiltrators, but since Sharon Agathon and members of the Final Five work for the Colonials, Battlestar Wiki's preference is to use "humanoid Cylon" (which Tricia Helfer often uses in interviews, but apparently more for convenience than an official name). Some of the resistance fighters on Caprica refer to the humanoid Cylons as "skin jobs," an homage to Blade Runner. William Adama refers to them as "humanoid models" in "Precipice", as does Samuel Anders in "No Exit". Sharon Valerii refers to them as "human models" in "Six Degrees of Separation" and Simon refers to them as "human Cylons" in "Torn"

↑Sharon Agathon steals back the Fleet's launch keys by infiltrating a Cylon base by using a Cylon data-font. Humanoid Cylons are seen operating a basestar in the episode "Torn" by touching an optical pad that illuminates these arm interfaces.